Finding the Fourth Proportional to 21,123.20, 31,690.79 and 10,580.49

Step by Step Solution

1. Step 1: Write the proportion equation
   21,123.20 : 31,690.79 = 10,580.49 : x
2. Step 2: Convert to fraction form
   21,123.20/31,690.79 = 10,580.49/x
3. Step 3: Cross multiply
   21,123.20x = 31,690.79 × 10,580.49
4. Step 4: Simplify right side
   21,123.20x = 335,304,033.78
5. Step 5: Solve for x
   x = 335,304,033.78/21,123.20
6. Step 6: Final answer
   x = 15,873.74